Vanadium pentoxide is a product of the processing of uranium and iron ores. Human exposure to during the handling and processing of these ores. The objectives of the planned prechronic (14-day & 13-week) inhalation studies is to determine the toxic effects of vanadium pentoxide aerosols in rats and mice. other objectives include the identification of target organs for the toxic effects of the chemical, determination of the no-effect-level, and determining differences in sensitivity between sexes and species. Data to be collected include morphologic and clinical pathology, sperm morphology and vaginal cytology, pulmonary and cardiovascular function indices, neurotoxic effects as well as renal function indices.